JP5226789B2 - Method, apparatus and system for optimizing cardiac preload based on measured pulmonary artery pressure - Google Patents

Description

  The present invention relates generally to cardiac pacing therapy, and more specifically to optimizing cardiac preload based on measured pulmonary artery pressure.

  Cardiac rhythm management devices have been developed that provide pacing stimulation to one or more heart chambers in an attempt to improve rhythm and coordinate at least one of atrial and ventricular contractions. A cardiac rhythm management device typically includes a circuit that senses signals from the heart and a pulse generator that provides electrical stimulation to the heart. Leads that extend into either the patient's heart chamber or the heart's blood vessels sense the heart's electrical signals and stimulate the heart with various therapies to treat cardiac arrhythmias. Coupled to an electrode for delivery.

  A pacemaker is a cardiac rhythm management device that delivers a timed series of low energy pace pulses to help the heart generate a contractile rhythm that maintains cardiac pumping efficiency. The pace pulse may be intermittent or continuous depending on the patient's needs. There are several categories of pacemaker devices that have various modes for sensing and pacing one or more heart chambers.

  Pacing therapy has been used in the treatment of various types of heart failure (HF). In general, HF is associated with a decrease in the pumping power of the heart, making it unable to deliver enough blood to meet the demands of peripheral tissues. HF can result in decreased breathing, loss of breathing, and fluid accumulation in the lungs and other body tissues. HF can affect the left heart, right heart, or both sides of the heart. For example, HF can occur when a decrease in heart muscle results in a decrease in at least one of dilation and contractility of the heart. Reduced contractility can reduce blood cardiac output and lead to increased heart rate. In some cases, HF is caused by asynchronous contractions of the left and right ventricles, such as atrial or ventricular dyssynchrony. As the left or right ventricle is affected, asynchronous contractions can significantly reduce the pumping efficiency of the heart.

  Pacing therapy may improve cardiac function by promoting synchronization of heart chamber contractions. This is commonly referred to as cardiac resynchronization therapy (CRT). Some cardiac pacemakers can deliver CRT by pacing multiple heart chambers. The pacing pulses are delivered to the heart chamber in a sequence that causes the heart chamber to contract synchronously, increasing the heart's pumping power and delivering more blood to the body's peripheral tissues. For premature failure of right and left ventricular contractions, a two ventricular pacing therapy may pace one or both ventricles. Alternatively, two atrial pacing or pacing of all four heart chambers may be used.

  Pacing therapy has proven valuable in stopping the physiological effects associated with decreased cardiac function. In some cases, pacing therapy has been shown to provide a process known as temporary or permanent correction of the physical decline of the heart resulting from heart disease, reverse remodeling. Thus, the identification and application of pacing therapies that contribute to reverse remodeling can help in extending the lifespan of patients who have experienced some form of heart failure.

  The present invention is directed to a system and method for optimizing cardiac preload based on measured pulmonary artery pressure.

  A method according to an embodiment of the present invention includes changing pacing parameters applied to the patient's heart during the short burst protocol for each iteration of the short burst protocol. Pulmonary artery pressure is measured during repeated short-term burst protocols. The optimal ventricular preload is determined based on the measured pulmonary artery pressure. The pacing therapy is provided using parameter values that are selected based on the determination of optimal ventricular preload. In one embodiment, the method includes altering pacing parameters applied to the patient's heart during the short burst protocol for each iteration of the short burst protocol. Pulmonary artery pressure is measured during the iteration of the short burst protocol, and the optimal ventricular preload is determined based on the measured pulmonary artery pressure. The pacing therapy is provided using parameter values that are selected based on the determination of optimal ventricular preload.

  In a more specific embodiment, the pacing parameters may include any combination of pacing delay, atrioventricular pacing delay, 2 ventricular delay, intraatrial delay, and pacing site of an implantable cardiac lead in the patient's atrium. . The method also includes selecting the length of the short burst protocol iteration so that the patient's baroreflex system does not adapt to the changed parameters of the pacing during the short burst protocol iteration.

  In another more specific embodiment, the method further includes measuring pulmonary artery pressure between iterations of the short burst protocol. In such cases, determining the optimal ventricular preload includes comparing the baseline pulmonary artery pressure with the pulmonary artery pressure measured during the iteration of the short-term burst protocol. In other arrangements, measuring pulmonary artery pressure during iteration of the short burst protocol includes measuring pulmonary artery diastolic pressure. In such cases, determining the optimal ventricular preload based on the measured pulmonary artery diastolic pressure may include determining the optimal ventricular preload based on the maximum value of the pulmonary artery diastolic pressure.

  In another more specific embodiment, determining the optimal ventricular preload based on the measured pulmonary artery pressure includes determining the optimal ventricular preload based on the maximum value of the pulmonary artery pressure. In one variation, providing a pacing therapy includes performing a free action optimization of a pacing interval applied to the patient's heart. In another variation, the method further includes changing the posture of the patient during a selected iteration of the short burst protocol iterations.

  In another embodiment of the invention, the medical system includes one or more electrodes for delivering pacing pulses to the patient's heart. The energy delivery and sensing unit is coupled to one or more electrodes. The system also includes a pulmonary artery pressure sensor capable of performing pulmonary artery pressure measurements and a memory configured to store at least pulmonary artery pressure measurement results. The controller is coupled to the memory, the pulmonary artery pressure sensor, and the energy delivery and sensing unit. The controller is configured to change the pacing parameters applied to the patient's heart by the energy delivery and sensing unit during the short burst protocol for each iteration of the short burst protocol. The controller stores pulmonary artery pressure measurement results made during the iteration of the short-term burst protocol and paces using parameter values selected based on the optimal ventricular preload determined by the stored pulmonary artery pressure measurement results Provide treatment.

  In more specific embodiments of the system, the pacing parameters may include any combination of pacing delay and electrode pacing sites. In one configuration, the controller is further configured to store pulmonary artery pressure measurement results between iterations of the short-term burst protocol to determine a baseline pulmonary artery pressure. In such cases, the optimal ventricular preload is determined by comparing the baseline pulmonary artery pressure with the pulmonary artery pressure measurements stored during the iteration of the short-term burst protocol.

  In a more particular embodiment of the system, the pulmonary artery pressure measurement includes a pulmonary artery diastolic pressure measurement. In other arrangements, the controller is further configured to determine an optimal ventricular preload based on a maximum pressure measurement made during a short burst protocol iteration. The controller is further configured to provide pacing therapy during the free behavioral optimization of the pacing interval applied to the patient's heart.

  In another embodiment of the invention, the medical system includes means for applying pacing to the patient's heart for multiple iterations of the short-term burst protocol. The pacing parameters vary for each iteration of the short burst protocol. The system is also selected based on means for measuring pulmonary artery pressure during multiple iterations of the short-term burst protocol, means for determining optimal ventricular preload based on the measured pulmonary artery pressure, and determination of optimal ventricular preload. Pacing parameter values are used to provide pacing therapy. The system may optionally include means for measuring pulmonary artery pressure between iterations of the short burst protocol to establish baseline pulmonary artery pressure. In such cases, the means for determining the optimal ventricular preload includes means for comparing the baseline pulmonary artery pressure with the pulmonary artery pressure measured during the iteration of the short-term burst protocol.

  The above summary of the present invention is not intended to describe each embodiment or every implementation of the present invention. Advantages and achievements will become apparent and understood by referring to the following detailed description and claims, taken in conjunction with the accompanying drawings, together with a more complete understanding of the invention.

FIG. 6 shows various waveforms illustrating cardiac cycles from which timing intervals may be measured to optimize cardiac preload according to embodiments of the present invention. 4 is a plot of data showing the interphase between left ventricular end diastolic pressure and pulmonary end diastolic pressure, according to an embodiment of the present invention. 4 is a plot illustrating varying pacing parameters in a short burst protocol, according to an embodiment of the present invention. 6 is a plot illustrating application of a short-term burst protocol to different pacing parameters according to an embodiment of the present invention. 4 is a flowchart illustrating various processes associated with a preload optimization method according to an embodiment of the present invention. 4 is a flowchart illustrating various processes associated with a preload optimization method according to an embodiment of the present invention. 4 is a flowchart illustrating various processes associated with a preload optimization method according to an embodiment of the present invention. FIG. 3 is a block diagram of a circuit that may be used to implement a preload optimization method according to an embodiment of the present invention. FIG. 6 illustrates a patient implantable device that may be used in connection with a preload optimization method according to an embodiment of the present invention.

  While the invention is amenable to various modifications and alternative forms, specifics thereof have been shown by way of example in the drawings and will not be described in detail below. It is understood, however, that the intention is not to limit the invention to the particular embodiments described. On the contrary, the invention is intended to cover all modifications, equivalents, and alternatives falling within the scope of the invention as defined by the appended claims.

  In the following description of the illustrated embodiments, reference is made to the accompanying drawings, which form a part hereof, and in which are shown by way of illustration various embodiments in which the invention may be practiced. It is understood that other embodiments may be utilized and structural and functional changes may be made without departing from the scope of the invention.

  Systems, devices, and methods according to the present invention may include one or more of the features, structures, methods, combinations thereof described below. For example, a device or system may be implemented to include one or more of the advantageous features and processes described below. Such a device or system need not include all of the features described herein, but may be implemented to include selected features that provide at least one of useful structures and functions. Is intended. Such a device or system may be implemented to provide various therapeutic or diagnostic functions.

  Embodiments of the present invention are directed to systems and methods for optimizing left ventricular (LV) preload using pacing therapy. Embodiments of the present invention are directed to making direct measurements of lung pressure during a short burst protocol and determining an optimal ventricular preload based on these pressure measurements. This optimization of preload may be at least one of being performed as part of an implantation procedure and as part of a free-acting CRT. For example, it may be desirable to increase LV preload in the short term as patient activity increases.

  A patient wearing an implantable cardiac rhythm management device may be exposed to a cardiac condition such as congestive heart failure (CHF). CHF is a situation in which the heart's ability to pump blood efficiently is substantially reduced. In some cases, CHF is caused by weakening of the wall muscle of at least one of the right and left sides of the heart by a general cause. In other cases, wall muscles are weakened by abnormal stretching during heart filling or contraction due to conditions such as arterial plaque, stress, smoking, and the like. If the myocardium on the left side of the heart is reduced, at least one of the left atrium and the left ventricle is enlarged. This situation is called left ventricular systolic dysfunction (LVSD).

  Patients with LVSD may experience a gradual decline in left ventricular hemodynamic performance. To compensate, the heart rate increases as the rest time between contractions decreases. Furthermore, dilation of cardiac tissue by LVSD can cause the ventricular depolarization signal to move slowly through the left side of the heart in the right ventricle. This causes the left ventricle to contract slightly later than the right ventricle, and further reduces the hemodynamic efficiency of the heart.

  A pacing therapy that coordinates at least one of atrial contraction and ventricular contraction may be used to increase cardiac efficiency in LVSD patients. Depending on the patient, pacing therapy may be applied via one or more electrodes positioned within one or more heart chambers. Multichamber pacing therapy may include left and right ventricular (two ventricular) pacing, ventricular and atrial (atrioventricular) pacing, and any combination of left and right atrial (intra-atrial) pacing. These pacing therapies may also utilize sensors that detect depolarization of the electrode site and adjust pacing appropriately.

  Multichamber pacing therapies such as CRT may improve left ventricular hemodynamic performance by reducing dyssynchrony. In particular, CRT in the form of biventricular pacing has been shown to improve hemodynamic status in the short term, reduce heart failure symptoms, and improve systolic function. Biventricular pacing has also been shown to cause reverse remodeling, which refers to improving left ventricular pumping efficiency by reducing some loss of cardiac physiology.

  One pacing strategy used to increase cardiac output is to optimize AV delay, such as to maximize left ventricular contractility (LVdp / dt). This contractility is maximized when the left ventricle is subjected to maximum end-diastolic volume or preload. This is known as the Frank Starling mechanism. The maximum left ventricular end diastolic volume (LVEDV) can be directly related to the left ventricular end diastolic pressure (LVEDP). Thus, pacing therapies that can be shown to maximize LVEDP also increase left ventricular cardiac output (LVEDV), thus increasing dp / dt, stroke volume, and preload.

  In some cases, it may be difficult to directly measure LVEDP. A more general approach is to indirectly measure LVEDP. It has been found that pulmonary artery diastolic pressure (PAD) may be used to estimate LVEDP. Referring now to FIGS. 1 and 2, there is shown the interphase between PAD and LVEDP / LVEDV that may be applied to methods, systems, and devices according to embodiments of the present invention. FIG. 1 shows various waveforms indicative of the cardiac cycle, in particular waveforms generated from electrocardiogram (ECG), PAD, and left ventricular pressure (LVP) measurement results. Measurement results useful for practicing embodiments of the invention may be generated using various sensors, waveforms, waveform features, and combinations of sensors, waveforms, and waveform features, and FIG. It will be understood that the measurement results associated with one and other figures are provided for non-limiting illustration only and should not be construed as limiting the scope of the invention.

  The waveform shown in FIG. 1 generally shows approximately three cardiac cycles as best seen in the ECG waveform 102. Waveform 104 represents pulmonary artery pressure and waveform 106 represents left ventricular pressure. Indicators 108, 110, and 112 indicate LVEDP points on the left ventricular waveform 106 for each of the three cardiac cycles. LVEDP 108, 110, and 112 are phase shifted from the PAD (eg, point 114) and there is a phase between the magnitude of LVEDP and the magnitude of PAD, as seen in the plot of FIG.

The data plot 200 shown in FIG. 2 is collected for a population of CRT patients and is useful for showing the interphase between pulmonary end-diastolic pressure (PAEDP) and LVEDP. The population for analyzing interphase preferably includes patients with similar left ventricular dysfunction. As can be seen from this population result, the linear relationship between LVEDP and PAEDP (shown as line 202) is
LVEDP = 0.88 ^* PAEDP + 7.49 [1]
Can be expressed as

  Equation [1] is merely an exemplary result showing the linear phase between LVEDP and PAEDP and is not necessarily required or used to estimate the actual LVEDP in embodiments of the present invention. Will be understood. In general, the methods and apparatus described herein may use PAEDP as a proxy for LVEDP measurements, such as determining whether the LVEDP pressure increases or decreases from a baseline value. The phase between PAEDP and LVEDP can be utilized by devices that can perform direct pulmonary artery pressure measurements. As described in more detail below, the implantable pacing system may include a pressure sensor capable of performing direct pulmonary artery pressure measurements.

  A system according to embodiments of the present invention may use lung pressure measurements, among other things, to improve hemodynamic heart performance by maximizing LV preload in the short term. PAEDP is an example of pulmonary artery pressure that may be optimized to optimize LVEDP / LVEDV, although other pulmonary pressure measurements such as pulmonary pulse pressure, pulmonary artery systolic pressure may be used for this purpose. Good. These methods for optimizing the LV preload are also applicable to systems capable of making a direct measurement of LVP. Similarly, other physical measurements that have a strong interphase with LVEDP / LVEDV may be used in systems according to embodiments of the present invention.

  In general, HF patients have high blood pressure as a result or effect of cardiac conditions. Thus, treating these HF patients involves lowering blood pressure over time. However, by maximizing LVEDP in the short term (eg, doing so over a short period of time), cardiac output increases temporarily and periodically, improving cardiac conditions (eg, reverse risk). Modeling can be induced). In general, short-term treatment relies on the short-term response of the heart to any variation in treatment parameters before the body's baroreflex can adapt.

  According to embodiments of the present invention, pacing parameters applied to the patient's heart are changed during multiple iterations of the short-term burst protocol. The parameters are different for each of the bursts, and the resulting change in lung pressure (or other measurement in phase with LVEDP / LVEDV) is observed. Lung pressure that occurs during the period between bursts may also be observed to establish a baseline reading. Assuming that one of the variations results in an optimal lung pressure reading, the value of that variation may be used as part of a short-term treatment to increase cardiac output. Determining the optimal reading from short-term burst therapy may have other applications such as determining the optimal placement of pacing leads. The plot 300 of FIG. 3 shows an example of how the pacing parameters may be changed to determine the optimal ventricular preload according to an embodiment of the present invention.

  The plot 300 includes a vertical axis 302 indicating PAD pressure (also referred to herein as PAD or PADP), in particular PAEDP. However, it will be appreciated that other pulmonary pressures (or other physiological measurements) known to have a strong correlation to LVEDP may be utilized. For example, the combination of PAEDP and another lung pressure performed during the cardiac cycle may provide improved estimation accuracy of LVEDP compared to that performed using only PAEDP. Horizontal axis 304 shows time, and variations in PAD 302 over time 304 are used to help optimize heart flow by increasing LV preload.

  As seen in plot 300, four burst intervals 306, 308, 310, and 312 are defined. The selection of the four intervals 306, 308, 310, 312 is optional and is done for illustration purposes. In general, safety considerations and measurement accuracy will dictate a reasonable number of intervals. As a result, the determination of the number and composition of intervals is usually done in an individual manner by the clinician.

  During each of these intervals 306, 308, 310, 312 the pacing parameter (P) is varied. This parameter may include delays applied to implantable pacing electrodes (eg, AV delay, VV delay), any other timing or electrical characteristics applied to such electrodes. Other parameters that may be changed include pacing electrode location. The location may be changed for characterization by physically moving the electrode (eg, during an implantation procedure). In closed-loop applications under free action, it is more common that the location may be changed by selecting a particular electrode of the multi-electrode lead.

As seen in FIG. 3, the parameter P is set to four different values 314, 316, 318, 320 for each burst interval 306, 308, 310, 312. As a result, the measured PADP can take on different values between intervals 306, 308, 310, and 312 represented by mean values 322, 324, 326, and 328, respectively. After the burst protocol is terminated, one of the average burst protocol values 322, 324, 326, and 328 may be determined to be optimal. Often, the optimum value of the average 322, 324, 326, and 328, here, could be a value having a maximum value represented by the value 324 in the P = _{v 2.} This value 324 corresponds to the highest short-term level of PADP 302 measured during treatment.

  The values 314, 316, 318, 320 are not only different from each other, but may also be different from the pacing parameters used (if any) during the interval between burst intervals 306, 308, 310, 312. These time intervals, referred to as sensing intervals 330, 332, 334, 336, 338, allow the heart to return to a normative state before, during, and after the application of burst intervals 306, 308, 310, 312. to enable. Measurements taken during the sensing intervals 330, 332, 334, 336, 338 may be used to determine the baseline value 340 of the PADP. In many situations, there is no pacing therapy applied during the rest intervals 330, 332, 334, 336, 338, and therefore the baseline 340 may represent a non-pacing value of PADP. In other cases, established values of pacing parameters may be applied during rest intervals 330, 332, 334, 336, 338. In this latter case, the values 322, 324, 326, 328 represent the change in PADP from the baseline pacing level due to the changed parameter P being changed.

  As previously mentioned, a number of different pacing parameters, including intracavity pace timing and lead location, may be varied during short-term burst therapy according to embodiments of the present invention. The phase in which these parameters result in maximum ventricular preload may be referred to herein as “characterization”. Characterization may be performed in a clinical situation where the patient's situation is actively monitored by the clinician. However, it may be possible to include some type of free-handed characterization, where free-handed characterization involves various (usually moderate) variations in parameters, and how many Altered under different patient situations (eg sleep, exercise, work), new parameter values are established or existing parameters are optimized. Any optimal parameters found during characterization can be used in a regular regime of treatment, usually by application with an implantable pacing system.

  Note that the change in the variables 314, 316, 318, 320 between subsequent burst intervals 306, 308, 310, 312 is only an example of how the characterization may be performed. In other examples, the variable P may be set to the same variable for consecutive or discontinuous bursts. In addition, the characterization protocol may consider various patient states, including posture (eg, standing, sitting, prone), activity levels, medications, and other situations or conditions. . The programmability of the implantable and / or external pacing device allows flexible adjustment of the characterization data to optimize the preload under various circumstances.

  As shown in FIG. 3, only a single parameter can be changed while characterizing a particular patient's response to that parameter. However, it is contemplated that patient response to multiple parameters may be determined by multiple characterization protocols as shown in FIG. Referring now to FIG. 4, plot 400 shows an example of three characterization results 402, 404, 406 that may be observed for a particular patient. Each result may be obtained by changing a single pacing parameter in a short burst protocol, and the parameter may be continuously variable or discretely variable. For example, the parameters associated with results 402 and 404 may be continuously variable (eg, timing), and the parameters associated with results 406 may be discretely variable (eg, activation on multiple electrode leads). Electrode location).

  Each result 402, 404, 406 is associated with a respective baseline value 408, 410, 412. For clarity, the baselines 408, 410, 412 and results 402, 404, 406 are plotted in separate vertical regions. However, under similar physiological circumstances, it may be considered that the baseline values 408, 410, 412 may be substantially the same. Results 402, 404, 406 may also be determined for a number of different patient situations, such as rest or work status, posture, medications, etc. In the example shown, results 402, 404, 406 have respective maximum PADP points 414, 416, and 418. The parameters associated with these maximum results 414, 416, 418 may be obtained directly from the results 402, 404, 406, or may be obtained by at least one of interpolation and extrapolation.

  In general, free-pacing pacing-optimized therapy can change parameter combinations based on characterization results 402, 404, 406. For example, the procedure may change both AV delay and location to increase the LV preload in the short term. Such parameter combinations may also be characterized together before being used for treatment. For example, an optimal value for each of the parameters may be selected from the results 402, 404, 406, and small variations may be introduced to ensure that the combination results in an optimal preload. In another example, both location and timing optimization may be performed during implantation to guide lead location, and then timing changes (and / or at least one of electrode selections) are free. It may be applied as part of a behavioral treatment.

For example, consider the case where AV delay and location are changed as part of a short-term treatment. The characterization indicates that AV _opt and LOC _opt are optimal values of AV delay and location found through single parameter characterization. AV- and AV +, _{respectively, AV opt} smaller, also be _a larger _{AV opt} small variations, LOC + and LOC- _is not large enough to _{LOC opt,} still show an increase of PAD in short burst protocol It may be an alternative location. Thus, another set of burst protocol characterizations uses some or all of (AV−, LOC−), (AV−, LOC +), (AV +, LOC−), and (AV +, LOC +), It may be determined whether the combination of AV _opt and LOC _opt is optimal, and if not optimal, an adjustment may be made.

  Considering now FIG. 5, a flowchart illustrating a procedure 500 for optimizing cardiac preload based on measured pulmonary artery pressure according to an embodiment of the present invention is shown. The procedure includes determining 502 different values of pacing parameter P. The parameter P may be any value that affects the application of electrical impulses to the heart tissue. Representative examples of P include AV delay, VV delay, lead location, and the like. The variable P may be continuous or discrete and the acceptable range of P may be patient specific.

Procedure 500 includes entering a loop 504 that is repeated n times, once for each value of P. For each iteration R of the loop 504, one is selected 506 pacing values, the selected value is annotated as P _R. Selected value of P _R is used 508 to apply pacing for A cardiac cycle, the value X _{R, A} is detected in the A period. The detected value X _{R, A} may be any value indicating at least one of LVEV and LVEDP. In general, X _{R, A} may be a direct measure of at least one of PAEDP and LVEDP. The number of iterations represented by A is selected such that the barometric function does not adapt to changes in stroke volume, but substantially affects LVEDP. After pacing 508 is applied, a sensing intervening period 510 is performed for the B heart cycle. Usually, the value of B will be much larger than A.

The same value of X (eg, PAEDP) detected in pacing phase 508 is at least detected in detection phase 510 for the B period. Measurements of these latter are represented as X _B. The sensing phase 510 may include pacing without pacing or using a pre-established intrinsic value for a particular patient. After detection 510, the value of R is incremented 512 and loop 504 continues for another iteration.

After n iterations 514, the X baseline value (X _BASE ) may be determined using measurements made during one or all of the sensing periods 510 (516). An optimal value for X (eg, maximum PAD) (X _OPT ) is determined 518 from values sensed during pacing period 508. X _OPT determination 518 also includes analyzing a baseline measurement X _BASE . A pacing therapy may then be provided using the actual or estimated optimal value of P (P _OPT ) determined based on X _OPT (520).

  Procedure 500 may use any parameter P known in the art. One useful application involves using AV delay as parameter P. Referring now to FIG. 6, a flowchart illustrating a procedure 600 for optimizing cardiac preload based on measured pulmonary artery pressure by changing AV delay (AVD) according to an embodiment of the present invention is shown. Procedure 600 includes using n predetermined AVD values. For example, the values may be 10%, 30%, 60%, and 90% of the patient's intrinsic PR timing. The AV optimization (AVO) procedure begins for a given lead location (604). The AVD is changed to one of n predetermined AVD values (606) and a pacing or sensing series 608 is performed. In this example, series 608 includes pacing for 6 heart cycles and sensing for 15 heart cycles. Series 608 may be repeated multiple times for the selected AV delay. A pacing PAD and an average (baseline) PAD are detected for each pacing and detection period (610). Sub-procedures 604, 606, 608, 610 are repeated 612 for n predetermined AVD values. After all predetermined AVD values have been exhaustively examined, the AVD is set to the value that generated the maximum pacing PAD (614).

  Considering now FIG. 7, a flowchart is shown illustrating a procedure 700 for optimizing cardiac preload based on measured pulmonary artery pressure by changing lead location according to an embodiment of the present invention. The procedure includes selecting the next one of the n lead locations (702) and initiating an AVO procedure 704 for the selected location (704). For example, a procedure such as that described in FIG. 6 may be used for AVO procedure 704. As a result of AVO procedure 704, an average and optimal PAD is established (706), and the procedure is repeated for the remaining locations (708). After all of the lead locations have been exhaustively examined, the lead location (and AVD) that provides the optimal (eg, maximum) PAD is used for treatment (710).

  The pacing optimization method of the present invention may be implemented in a variety of medical diagnostic devices and systems, including implantable and patient-external devices and systems. For example, the pacing optimization method of the present invention can be used exclusively by implantable devices (eg, pacemakers, ICDs, CRT devices), by patient external systems (other than cardiac electrodes or leads), or implantable and patient-external. It may be implemented in a distributed manner by both devices or systems. In the context of a patient external approach or a distributed approach, various external systems may be used, such as at least one of a programmer and a networked system such as an advanced patient management system.

  Referring now to FIG. 8, a block diagram shows a circuit that implements a pacing optimization method according to an embodiment of the present invention. One or more cardiac electrodes 802 may be positioned or disposed at multiple locations within the heart chamber or vasculature. In the context of an electrode implantation procedure, a candidate pacing site may be evaluated or optimized using a lead that includes one or more electrodes. In the context of post-implantation evaluation, one or more implantable pacing sites may be evaluated or optimized.

  One or more sensors 804 are configured to sense a physiological factor indicative of the patient's hemodynamic status. Useful sensors 804 include, among other things, one or more sensors that detect heart sounds (eg, microphones, accelerometers), pressure sensors (eg, left atrial pressure sensors such as pulmonary artery pressure sensors, left / right ventricular pressure sensors), And a cardiac output impedance sensor. The signal generated by the one or more sensors 804 may be communicated to a hemodynamic signal processor 806 that processes the sensor signals for use by the controller 808.

  Controller 808 is coupled to hemodynamic signal processor 806, memory 810, cardiac signal sensing circuit 812, and pacing therapy circuit 814. The memory 810 is configured to store at least one of program instructions and data. Furthermore, the stored information may be used to provide a log of events for later display or analysis. Memory 810 may be configured to store a preload optimization algorithm 816 of the type described above. Alternatively, the optimization algorithm 816 may be stored on a device or system external to the patient. Controller 808 executes program instructions to implement a ventricular preload optimization procedure according to an embodiment of the invention.

  The controller 808 is preferably coupled to the communication circuit 818, which allows the device to communicate with other devices 820, such as a programmer external to the patient or an advanced patient management system. In some implementations, an advanced patient management (APM) system is used to generate patient population data by which a preload optimization algorithm may be trained. May be collected. This data may be collected from a number of CRT patients. An APM system or programmer may also be used to implement or facilitate the implementation of the pacing site evaluation method of the present invention, particularly in the context of electrode implantation procedures.

  Referring now to FIG. 9, an embodiment of the present invention implemented by use of an implantable heart treatment device 900 is shown. The treatment device 900 includes a cardiac rhythm management circuit enclosed within an implantable housing 901. The CRM circuit is electrically coupled to the intracardiac lead system 910. Certain portions of the intracardiac lead system 910 are shown inserted into the patient's heart. The lead system 910 may be in, on, or in one or more heart chambers for at least one of sensing electrical signals from the patient's heart and delivering pacing pulses to the heart. It includes cardiac pace / sense electrodes 951-956 positioned around it. Intracardiac sense / pace electrodes 951-956 are used to sense and / or pace one or more heart chambers of the heart, including the left ventricle, right ventricle, left atrium, and / or right atrium. May be. The lead system 910 may include one or more defibrillation electrodes 941, 942 for delivering a defibrillation / cardioversion shock to the heart.

  The left ventricular lead 905 incorporates a plurality of electrodes 954a-954d positioned at various locations in, on or around the left ventricle. Stimulating the ventricle at multiple locations or at a single selected location can result in increased cardiac output for patients suffering from HF. According to various embodiments described herein, one or more of electrodes 954a-954d are selected for pacing the left ventricle. In other embodiments, a lead having a plurality of pacing electrodes positioned at a plurality of locations within the heart chamber, as shown by left ventricular lead 905 of FIG. 9, can be any or all of the heart chambers of the heart chamber. It may be embedded inside. A set of electrodes positioned within one or more heart chambers may be selected. Electrical stimulation pulses may be delivered to the heart chamber by selected electrodes according to a timing sequence and output configuration that enhances cardiac function.

  Certain portions of the housing 901 of the implantable device 900 may optionally serve as one or more cans or indifferent electrodes. The housing 901 may be configured to facilitate a removable attachment between the one or more leads and the housing 901. The housing 901 of the treatment device 900 may include one or more can electrodes 981b. The header 989 of the treatment device 900 may include one or more indifferent electrodes 981a.

  At least one of the housing 901 and the header 989 may include one or more hemodynamic sensors 982, such as an accelerometer or a microphone. One or more cardiac leads 910 or separate sensor leads may incorporate one or more hemodynamic sensors, such as a pulmonary artery pressure sensor. Cardiac electrodes and / or other sensors disposed in or on the housing 901 or lead system 910 of the treatment device 900 include transthoracic impedance, respiratory rate, minute ventilation, heart rate, cardiac dyssynchrony, Activity, posture, blood chemistry, oxygen saturation, heart sound, wall stress, wall tension, hypertrophy, interelectrode impedance, electrical delay (PR interval, AV interval, QRS width, etc.), activity, heart chamber pressure, cardiac output, Signals used for the detection and / or measurement of various physiological parameters, such as temperature, heart rate variability, depolarization amplitude, depolarization timing, and / or other physiological parameters may be generated. In some embodiments, information derived from such signals is incorporated into an optimization algorithm used to provide short-term optimization of left ventricular preload in response to changing CRT pacing parameters. It is conceivable.

  In some configurations, the implantable device 900 is configured with one or more transthoracic impedance sensors that may be used to acquire a patient's respiratory waveform and / or acquire other respiratory related information. It may be complicated. The transthoracic impedance sensor may include, for example, one or more intracardiac electrodes 941, 942, 951-956 positioned in one or more heart chambers. Intracardiac electrodes 941, 942, 951-956 may be coupled to an impedance drive / sense circuit positioned within the housing 901 of the treatment device 900. Information from the transthoracic impedance sensor may be used, among other uses, to adapt to the rate of pacing to accommodate patient activity or metabolic demand.

  A communication circuit is disposed within the housing 901 to facilitate communication between the CRM circuit and an external patient device such as an external programmer or advanced patient management (APM) system. The communication circuit may also be a one-way or two-way communication with one or more implantable, external, cutaneous, or subcutaneous, physiological or non-physiological sensors, patient input devices, and / or information systems. May be made easier.

  In some embodiments, therapy device 900 may include circuitry for detecting and treating cardiac tachyarrhythmia by defibrillation therapy and / or anti-tachyarrhythmia pacing (ATP). Good. Configurations that provide defibrillation capabilities may utilize defibrillation coils 941, 942 to deliver a high energy shock to the heart to terminate or reduce tachyarrhythmia.

  In some embodiments, the implantable treatment device 900 may include pacing electrode (s), timing sequences, and / or amplitudes or pulses applied by one or more electrodes within one or more heart chambers. A circuit for selecting a waveform output configuration (collectively referred to as a pacing output configuration) may be included. For example, a pacing site evaluation procedure may be implemented to evaluate optimal pacing after implantation to maximize ventricular preload. Changes may be made in timing parameters associated with pacing (eg, AV delay) to maximize ventricular preload. Any combination of pacemaker parameters may be used for characterization of parameters to determine optimal preload conditions and may be used to provide therapy using these parameters. For example, in a pacemaker equipped with a plurality of pacing electrodes respectively disposed at a plurality of pacing sites in the heart chamber, one or more electrodes, temporal sequences, and / or pulse waveform characteristics for delivering pacing Can be used to enhance the contractile function of the heart chamber by optimizing / maximizing ventricular preload.

  Multi-site pacemakers such as those shown herein are capable of delivering pacing pulses to multiple locations in the atrium and / or ventricle during the cardiac cycle. Some patients may benefit by activating certain portions of the heart chamber, such as the ventricle, at different times in order to distribute pumping loads and / or depolarization sequences to different areas of the ventricle. Multi-site pacemakers have the ability to switch the output of pacing pulses between selected electrodes or groups of electrodes within the heart chamber during different cardiac cycles. For example, a pacing pulse may be delivered to the heart chamber during a cardiac cycle at a specified location and at a specified time to increase systolic synchrony. The amplitude of the pacing pulse, the pulse duration, the anode / cathode polarity, and / or the waveform may also be modified to enhance the pumping function, as described above.

  Various changes and additions can be made to the preferred embodiments described above without departing from the scope of the invention. Accordingly, the scope of the invention should not be limited by the particular embodiments described above, but should be defined only by the appended claims and their equivalents.

Claims (6)

A medical system,
One or more electrodes for delivering pacing pulses to the patient's heart;
An energy delivery and sensing unit coupled to the one or more electrodes;
A pulmonary artery pressure sensor capable of measuring pulmonary artery pressure; and
A memory configured to store at least the pulmonary artery pressure measurement results;
A controller coupled to the memory, the pulmonary artery pressure sensor, and the energy delivery and sensing unit, the controller comprising:
For each iteration of the short burst protocol, change the value of the pacing parameter applied to the patient's heart by the energy delivery and sensing unit during the short burst protocol;
Providing an intervening period of detection between each iteration of the short burst protocol, including no pacing or pacing with a previously established endogenous value;
Storing the pulmonary artery pressure measurement results made during the repetition of the short-term burst protocol and during the intervening period of the detection ;
A medical system configured to provide pacing therapy using a value of the parameter selected based on an optimal ventricular preload determined by the stored pulmonary artery pressure measurement.   The medical system of claim 1, wherein the parameters of pacing include one or more of atrioventricular delay, intraatrial delay, and two ventricular delay.   The medical system according to claim 1, wherein the parameter of pacing includes a pacing site of the electrode. Wherein the controller is further configured to determine the pulmonary arterial pressure baseline, the optimum ventricular preload, the baseline pulmonary artery pressure, compared with the pulmonary arterial pressure measurement result stored in repetition of the short-term burst protocol The medical system of claim 1, as determined by:   The medical system according to claim 1, wherein the pulmonary artery pressure measurement result includes a pulmonary artery diastolic pressure measurement result. The repeat length of the short burst protocol is selected so that a patient baroreflex system does not adapt to the altered parameter of pacing during the repeat of the short burst protocol. Medical system.

Images